zkpython is currently limited to a max of 256 total handles - not 256 open handles, but rather 256 total handles created
over the lifetime of the python application.
In general this isn't a real issue, however in the case of a long lived application which polls the cluster periodically (closing
the session btw calls) this is an issue.
it would be great if the slots could be reused? or perhaps a more complex structure, such as a linked list, which would allow
dynamic growth/shrinkage of the handle list.